In recent years, there has been a dynamic growth in piggyback carloadings, i.e. the mounting and shipping of highway trailers on railway flatcars. Over the years, flatcars for this purpose have been made larger and larger, and are currently being made in a standard 89-foot, 4-inch length, the maximum allowable length for a rail car according to A.A.R. (Association of American Railroads) rules. Such cars are provided with two trailer hitches and are intended to carry two highway trailers in tandem arrangement. Recently, highway trailers have been made in ever increasing lengths, up to 45 feet and 48 feet (with the possibility of up to 50 feet in the near future). It will be evident that a pair of highway trailers of such length cannot be mounted on a standard 89-foot, 4-inch railway flatcar without modification of the flatcar, and, as a result, only one 45-foot or 48-foot highway trailer can be accommodated on such a car.
This is an undesirable situation for a number of reasons. First of all, it means that there is a considerable waste of valuable cargo-carrying space per car. In a train of such cars, such waste of cargo-carrying space is multiplied. This also means that each highway trailer is being carried on a railway car of greater size and weight than would otherwise be required. Aerodynamically, it is advantageous to locate the highway trailers as close together as possible, end-to-end, which is not possible under these circumstances.
At the present time, a number of railroads have an over-abundance of older box cars which have been replaced by box cars of greater length and greater capacity. If such box cars have a length of at least 50 feet, most of them are convertible to flatcars capable of accommodating a single highway trailer of a length ranging from about 40 feet to 48 feet, even if the trailer is provided with a front mounted or nose mounted refrigerator unit (and trailers of 50-foot length provided with an underslung refrigerator unit). The present invention is directed to such conversion flatcars and a method of producing them.
The teachings of the present invention can be applied to many types of box cars produced by a variety of manufacturers. The primary constraint is that the box car have a length of at least 50 feet. For purposes of an exemplary showing, the invention will be taught in terms of the conversion of a 50-foot, 50-ton box car. It will be understood that box cars of greater length and greater tonnage capacity could be used. For purposes of description, a 50-foot, 50-ton box car has been selected for a number of reasons. First of all, there is currently an over-abundance of such cars. Secondly, such cars are not in as great demand for service, as are cars of greater size and capacity, such as 50-foot, 70-ton cars; 60-foot, 70-ton cars; and so on.
In the practice of the present invention, the sides, ends and roof of the box car are removed at substantially the floor line of the car. It will be understood that the underframe of such a car derives some of its strength in service from the sides, ends and roof, having been initially designed with these members in mind. Therefore, a part of the conversion process entails the appropriate strengthening of the car underframe for the loads anticipated, so that the conversion car can meet A.A.R. standards for such cars.
That some box cars constitute better candidates for conversion than others, will be readily apparent to one skilled in the art. For example, box cars having oversized doors, double doors or staggered doors will initially have heavier side sills of greater strength than similarly-sized box cars having single 8-foot wide doors on each side. While some additional changes or modifications may have to be made, depending upon the nature of the box car being converted, the teachings of the present invention are generally applicable to any box car constituting a reasonably good candidate for conversion.